SOIL-WATER, PLANT-GROWTH, AND YIELD OF STRIP-INTERCROPPED CORN

Strip-intercropping soybean (Medicago sativa L.) with corn (Zea mays L .) decreases yields in soybean border rows. Separating corn and soybea n with a small grain strip could decrease competition for soybean and improve overall yield. This study was conducted to determine the effec t of a small grain strip on corn and soybean performance and on soil w ater content in the corn strip. Corn and soybean were strip-intercropp ed (rows running north-south) with oat (Avena sativa L.) in 1991 and b arley (Hordeum vulgare L. emend. Lam.) in 1992 on a ridge-tilled Dalho usie silt loam (fine, mixed, mesic Typic Endoaquoll) in Nepean, Ontari o. Both years, plant height varied among corn rows. In 1992, plant dev elopment was faster and grain moisture at harvest was lower in corn bo rder rows than in non-border rows. In 1991 and 1992, soil water was de pleted earlier in the corn and small grain interrow than in the corn a nd soybean interrow. In 1991, a hot and dry growing season, yield of t he corn row next to small grain was 20% lower than that of other corn rows. In 1992, a wet and cool growing season, both corn border rows yi elded yielded 26% more than nonborder rows, partly due to increased nu mber of ears per plant. Both years, soybean yield in the row bordering small grain was similar to that of nonborder rows but yield in the ro w bordering corn was 18% lower than that of nonborder rows. Including a small grain in corn and soybean strip-cropping can be beneficial if soil moisture is not limiting.